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(No Model.) 2 Sheets-Sheet 1,

' J. H. B UNNELL.

` TELBGRAPHIG SOUNDBR.

N0.'538,816. Patented May 7, 1895.

(No Model.) 8- sheetssheet` 2.

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UNITED STATES PATENT OFE'TCE.

JESSE H. BUNNELL, OF NEW YORK, N. Y.

TELEGRAPHIC SOUNDER.

SPECIFICATION forming' part ofk Letters Patent No. 538,816, dated May 7, 1895. Application led April 19, 1893. Renewed June 21, 1894 Serial No. 515,317. (No model.)

ers, the object being to increase theloudness and clearness of the sounds due to the blows of the armature, and thus to render the instru ment more effective than lthose heretofore employed. v

In carrying out my inventionI mount the anvil upon which the armature strikes upon a sounding board or resonator, andso support the magnet cooperating with the armature, that the mass of metal of which it is composed cannot check or dampen the freedom of vibration of the anvil and its resonator. In addition to the main feature just referred to, 0f increasing the volume and clearnessof sound emitted, there are certain other features of importance embodied in my instrument, more especially, the devices for securing convenience and delicacy of adjustment between the armature and its actuating magnet. v

My invention consists in its broadest aspect of a telegraphic sounder whose operating electro-magnet is adjustably supported that neither its mass nor its connection with the base interferes with the freedom of vibration i ments.

of the anvil or its attached resonator.

Other incidental features of novelty will be more particularly hereinafter described and will be definitely indicated in the claims appended to this specification.

In the accompanying drawings, which illustrate the invention, Figure l is a side elevationrof a sounder embodying my improve- Fig. 2 is a sectional view taken on the plane indicated by the line 2 2 of Fig. l, part of the armature-bearing being also shown in section for the sake of clearness. Fig.,3 is a sectional view taken on the plane indicated by the line 3 3 of Fig. l, and Fig. 4 is a plan view of the resonant base or sounding-board for the instrument. v l

Referring to the drawings, A indicates a bed or foundation plate preferably made of hard wood or other light and cheap material, and providedwith three or more supporting feet for holding it free from contact with the table or other supporting medium. Above this bed-plate is mounted a resonator B preferably of metal and supported at aplurality of'points upon the bed-plate A by means of` screws or other devices which serve to maintain it in a fixed relation thereto. Mounted upon the resonator between two of its points of support is the anvil C whichfco-operates with and receives the impact of the armature lever of the sounder.' This anvil may be fixedly mounted upon one or more supporting feet preferably more than one, by which, as indicated at D, E, the vibrations due t0 the impact of the armature lever, are communicated to the resonator. Atcertain points of the resonator closely adjacent to its points of connection withvthe bed-plate, are iixed the two extremities E, F of an arched standard or support hereinafter termed the trunnionyoke, for the armature and electromagnet. The electro-magnet is connected by its yoke with a movable cradle G herein shown as pivotally connected to the trunnion yoke at points H, H', through which extend adjustable setscrews I, I which form the hearings for,the axis of the lever K to which the armature is affixed. The cradle G is provided with extensions L, L to which the yoke of the electro-magnet is rigidly afxed. Secured to the bed-plate A is an angular support M provided with two upward extensions, one of 'which serves as an abutment for a tension spring for the cradle as indicated, while the other serves as a support for an adjusting screw N for the cradle and a tension key O for the armature. The armature lever at the points where it makes contact with the anvil is provided with the usual upper and lower adjusting screws and jam nuts, as indicated. From this construction it will be seen that the vibrations communicated bythe blow of the armature in the anvil are communicated to a resonator which has great freedom of vibration. AThe electro-magnetand the armature both being pivotally supported, and having their points of connection with the resonator at points very close to its points of attachn ment to the bed-plate, interfere to a minimum IOO degree with its vibrations, and hence a very loud and clear sound is emitted even by a comparatively weak stroke of the armature lever.

In the usual form of construction, in which the electro-magnet is rigidly xed to the same plate which carries the anvil support, the vibrations of the anvil are dampened very considerably by the mass of metal forming the electro magnet. In my construction the weight of the electro-magnet bears upon the resonator at nodal point, at which a minimum interference of vibration is created, and in addition to this the electro-magnet swings in a cradle independently mounted, which almost entirely eradicates any dalnpening inluence upon the vibrations communicated to the resonator. Moreover the intensity of sound is materially augmented by the base A, the sides of which vibrate simultaneously with the resonator plate, thus making the resonant effect compound in action.

Another advantage resulting from the mode of supporting the electro-magnet herein described is that a great delicacy of adjustment is possible, because the adjusting screw N acts upon the end of a long lever, admitting of a very accurate and minute adjustment because a considerable number of turns of the screw will only shift the core of the magnet very slightly toward the armature. An approximate adjustment may be made by the screws mounted on the anvil and armature near the end of the latter, after which the more accurate adjustment may be accomplished by means of the screw Y.

The features which have been described render the apparatus peculiarly well adapted for long lines having a comparatively feeble current, but it is to be understood that the invention is not restricted to such use.

I claim as my invention- 1. A telegraphic sounder comprising a resonator mounted upon a base at a plurality ot points, an anvil rigidly connected to the resonator between said points, and an electromagnet and armature mounted upon the-resonator closely adjacent to its points of support, whereby said resonator is free to vibrate independently of the inertia of the electromagnet.

2. A telegraphic sounder comprising an anvil mounted upon a resonant base between its points of support, a support for the armature mounted closely adjacent to the points of support, an electro-magnet connected at or near its yoke, with a movable cradle similarly related to the points of support for the resonant plate, and a device for adjusting the electro-magnet and its cradle.

3. In a telegraphic sounder, the combination of its vibrating armature, a trunnionyoke in which the armature is pivotally mounted, a cooperating electro-magnet also carried upon the trunnion yoke, and a resonator upon which the anvil of the armature is mounted.

4. A telegraphic instrument comprising a pivoted armature having suitable limiting stops, and a cradle to which the electro-magnet is rigidly secured at or nearits yoke, said cradle being pivoted concentrically with the armature to admit of adjustment toward or from the armature, and an adjusting device for shifting the position of said cradle.

5. A telegraphic instrument comprising an armature provided with adjustable limiting stops, a cradle upon which the electro-magnet is mounted, said cradle being pivoted concentrically with the armature, andan adjusting screw near the free end of the cradle for the purpose described.

6. In a telegraphic sounder, a resonator plate supported ata plurality of points within its outer edges and not in contact with the main base at any point or points excepting those required for the supports, leaving said edges free to respond to vibrations communicated by an anvil seated within the area inclosed by said supporting points.

In testimony whereof Ihave hereunto subscribed my name this 18th dayoi:` April, A. D. 1893.

JESSE H. BUNNELL.

Witnesses:

CAROLINE E. DAVIDSON, JEssIE B. KAY. 

